In image pickup apparatuses including a generic CMOS image sensor, an imaging lens is used, and a solid-state imaging device is disposed at a focal position of the imaging lens.
Then, light, which originates from a subject and is captured by the imaging lens, is optically processed in an optical system so as to be easily converted into an electric signal in the solid-state imaging device. Thereafter, the light is guided into the photoelectric conversion side of the solid-state imaging device, and an electric signal, which can be obtained by photoelectric conversion through an imaging device, is subjected to a predetermined signal processing through a circuit for signal processing at a latter stage (for example, see “Introduction to CCD Camera Technology2, Takemura Yasuo, first edition, Corona Co., August 1998, p. 2-4).
These kinds of image pickup apparatuses are not only used as camera systems, each of which is a single unit, such as digital still cameras, but also, recently, have been used by being built in small portable devices such as mobile phones.
Hence, in order for the image pickup apparatuses to be built into the mobile phones and the like, there has been a strong demand for reduction in size, weight, and cost of the image pickup apparatus.
That is, by building small, lightweight, and low-cost image pickup apparatuses therein, it is possible to significantly contribute to reduce the size, the weight, and the cost of the small portable devices such as mobile phones.
Incidentally, generic image sensors are unable to capture images on both sides thereof by using a single sensor, but in recent years, as backside illumination image sensors, in which light is made to be incident from the back side thereof on which the elements and the like are not formed, have been newly developed, some image sensors have detection abilities on both sides thereof.
However, this sensor is thin, and thus it is necessary for the sensor to have an opaque support substrate called a support silicon (Si). For this reason, it is difficult to use both sides thereof as sensors.
Further, such an object, referred to as an in-camera or an out-camera, needs an individual interface with an ISP, an application processor, and a baseband chip. For this reason, double costs are needed for adjustment and inspection of each connection component.
Further, as a new method of fabricating a camera module with an intention of reducing costs, there is a wafer level camera module. In this method, a wafer-like lens array is attached to a sensor wafer together with a wafer, and the wafer is cut together with the lens into each individual piece, thereby considerably reducing the cost thereof.
However, in this structure, when the wafer lenses are attached to both sides of the double-sided sensor, the extraction electrodes cannot be formed.